The present invention relates to an apparatus and method for applying glue, and, in particular, to an apparatus and method for applying glue through an apparatus having a nozzle which can be purged of glue by the passage of water therethrough.
Current methods of forming ductwork include using a coil line of steel which is bent to form a duct typically 1-2 meters in diameter. Prior to bending the steel, glue is applied to the steel coil for use in adhering insulation to the duct. Typically, a gluing system is installed at the end of the coil line. As a sheet of metal proceeds down the coil line, the glue system applies ribbons of glue to the metal coil passing therebeneath through a tube which has extruding orifices. Thereafter, the insulation is applied to the metal coil.
Conventional gluing systems have disadvantages which limit their usefulness. For example, manual cleaning is typically necessary to remove glue from the extruding orifices. In addition, after the glue is turned off subsequent to a glue application process, there may be as much as a cup of glue left in the extruding line. If the coil line is shut down for any period of time, the glue will harden within the extruding orifices and this requires manual purging of the glue. In order to perform such a purging operation, the extruding orifices need to be taken off (i.e., removed or disconnected from the tube) and placed in a bucket of water to remove the glue. This operation is manually intensive and tends to be messy.
In accordance with the present invention, a glue system is provided for supplying glue through a spray nozzle to a workpiece which includes a water supply for purging residual glue from the spray nozzle after a glue application process. Optimally, the temperature of the glue is maintained at a desired glue temperature to prevent the glue from curing. In addition, optimally, the water is kept at a desired water temperature thereby further aiding to keep the glue at the desired glue temperature and to optimize the purging of glue from the spray nozzle.
In accordance with one aspect of the present invention, an apparatus is provided for applying glue which comprises an outer conduit surrounding an inner conduit, defining a first channel therebetween. The inner conduit supplies glue and the first channel supplies water. The outer conduit and the inner conduit are slidably engaged with one another and the outer conduit has at least one outer conduit orifice. At least one spray nozzle is in communication with a respective outer conduit orifice. A slide conduit orifice valving provides selective communication of the outer conduit orifice with the inner conduit orifice and the first channel.
In one specific embodiment, the slide conduit orifice valving comprises an intermediate conduit disposed between the inner conduit and the outer conduit which is stationary (i.e. secured) relative to the inner conduit. The intermediate conduit has a water orifice in communication with the first channel and the intermediate conduit has a glue orifice in communication with the inner conduit orifice. The outer conduit is slidable relative to the intermediate conduit to selectively align the outer conduit orifice with the glue orifice, the water orifice, or neither orifice.
In accordance with another aspect of the present invention, an apparatus is provided for applying glue which includes an outer conduit surrounding an inner conduit. The inner conduit supplies glue and has at least one inner conduit orifice. The outer conduit has at least one outer conduit orifice. An intermediate conduit is disposed between the inner conduit and the outer conduit. The intermediate conduit defines a first water channel between the intermediate conduit and the inner conduit, and a second water channel between the intermediate conduit and the outer conduit. The intermediate conduit is secured relative to the inner conduit for movement therewith, has a water orifice in communication with the first channel and the second channel, and has a glue orifice in communication with the inner conduit orifice, whereby relative movement of the inner and intermediate conduit relative to the outer conduit is used to selectively align the outer conduit orifice with the glue orifice, with the water orifice or with neither the glue or water orifice. A glue circulation system circulates glue through the inner conduit. A water circulation system supplies water to the first channel and the second channel. At least one nozzle is in communication with the at least one outer conduit orifice. In one further specific embodiment, a plurality of nozzles are provided, each nozzle being associated with a respective one of a plurality of outer conduit orifices.
In accordance with another aspect of the present invention, a method is provided for applying glue to a workpiece including selectively providing glue and water to at least one selected nozzle. Glue is circulated through an inner conduit at a desired glue temperature and water is circulating through a channel defined between the inner conduit and an intermediate conduit at a desired temperature. The intermediate conduit has a glue orifice in communication with the glue and a water orifice in communication with the water. An outer conduit orifice of an outer conduit is selectively aligned with the glue orifice, the water orifice or neither orifice of the intermediate conduit whereby either glue, water or neither is supplied to the outer conduit orifice. Glue is applied to the workpiece when the outer conduit orifice is aligned with the glue orifice by supplying glue from the inner conduit, through the glue orifice, the outer conduit orifice and out a nozzle associated with the outer conduit orifice. Glue is purged from the nozzle when the outer conduit orifice is aligned with the water orifice by supplying water from the first channel and the second channel through the outer conduit orifice and out the nozzle.
In accordance with yet another aspect of the present invention, a method is provided for applying glue to a workpiece including circulating glue through an inner conduit at a desired glue temperature and circulating water through a first channel formed between the inner conduit and an intermediate conduit, and through a second channel formed between an outer conduit and the intermediate conduit. The intermediate conduit has a glue orifice in communication with the glue and a water orifice in communication with the water. An outer conduit orifice of the outer conduit is selectively aligned with the glue orifice, the water orifice or neither orifice of the intermediate conduit by sliding the outer conduit relative to the intermediate conduit whereby either glue, water or neither is supplied to the outer conduit orifice. Glue is applied to the workpiece when the outer conduit orifice is aligned with the glue orifice by supplying glue from the inner conduit, through the glue orifice, the outer conduit orifice and out a nozzle associated with the outer conduit orifice. Glue is purged from the nozzle when the outer conduit orifice is aligned with the water orifice by supplying water from the first channel and the second channel through the outer conduit orifice and out the nozzle.
A key feature of the present gluing system is provided by an automatic water flushing system for purging of glue from the spray nozzles. Preferably, a continuous circulation of water, at a desirable water temperature, is used to purge glue from the spray nozzles. The desired (typically elevated) water temperature helps to maintain the glue at a desired glue temperature and assists in dissolving the glue for better cleaning of the spray nozzle. Further, the continuous circulation of water assists in minimizing the water consumption. An advantage of the automatic water flushing system is an automated and simplified method for clearing the spray nozzles of glue.
An additional feature of the present gluing system is provided by the continuous circulation of glue throughout the gluing system. This continuous circulation prevents inconsistencies in the glue. Further, the circulation of glue prevents build-up of glue within the system. In addition, the present gluing system can be used to maintain the glue at a constant temperature which is desirable in preventing the glue from hardening within the gluing system.
A further feature of the present invention is provided by the slide tube orifice valving. Preferably, the slide tube orifice valving provides a three-position valve for communicating glue, water or neither through the spray nozzles. Further, the slide tube orifice valving provides for airless operation of the spray nozzle when applying glue to a workpiece or during the purging of glue with water. In addition, the slide tube orifice valving provides for minimum glue waste, minimum flushing of the spray nozzles with water, and minimal clogging of the spray nozzles.
Further features and advantages of the present invention will be set forth in, or apparent from, the detailed description of preferred embodiments thereof which follows.